The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Some vapor-based reaction technologies and their associated applications, such as dielectric constant (k) recovery and atomic layer deposition (ALD), require expensive precursor gas. These processes involve exposing a substrate to the precursor gas at a target pressure, allowing the substrate to soak and then dumping the precursor gas (an expose/soak/dump sequence). To minimize the use of the precursor gas, significant effort has been expended to minimize reaction volumes, which reduces precursor gas consumption per wafer. However, the smaller reaction volumes may cause other undesirable reactor design compromises, which may increase cost on a per-wafer pass basis.
Referring now to FIG. 1, a first reaction volume 10 is shown. A pedestal 12 is arranged in the first reaction volume 10 and provides support for a substrate 14 such as a semiconductor wafer. Precursor gases 20-1, 20-2, . . . , and 20-N (collectively precursor gases 20) are supplied via valves 22-1, 22-2, . . . , and 22-N (collectively valves 22) to the first reaction volume 10, wherein N is an integer. Purge gas 24 is supplied via a valve 26 to the first reaction volume 10. A pump 30 may be used to selectively draw precursor gas and/or purge gas from the first reaction volume 10.
Referring now to FIG. 2, a method for operating the first reaction volume 10 is shown. At 31, N=1. At 32, the substrate 14 is arranged in the first reaction volume 10 and is exposed to a first precursor gas at a target pressure. At 34, the substrate 14 is allowed to soak in the precursor gas for a predetermined period. At 36, the precursor gas is purged from the first reaction volume 10 and discarded. At 38, if another precursor gas is to be used, control returns to 32. Optionally the sequence may cycle via 39 and 41. Otherwise the process ends.